Part 91

Part 91. It is a foundational section of the Federal Aviation Regulations (FARs) administered by the Federal Aviation Administration (FAA) that establishes the general operating and flight rules for civil aircraft within the United States. These rules apply to a vast majority of non-commercial aviation activities, from personal flights in a Cessna 172 to complex corporate jet operations, unless specifically superseded by more stringent regulations like Part 135 or Part 121. The provisions form the essential regulatory framework for visual flight rules (VFR) and instrument flight rules (IFR) operations, governing everything from preflight actions to right-of-way protocols in the National Airspace System.

Overview and Scope

The primary scope encompasses all civil aircraft operations not conducted as commercial air carriers or commercial operators, effectively serving as the default set of rules for private and business flying. Its applicability extends to operations within the sovereign airspace of the United States, including territories and possessions, and to U.S.-registered aircraft operating internationally unless preempted by International Civil Aviation Organization (ICAO) standards or local regulations. Key exclusions are operations conducted under the stricter, passenger-carrying rules of Part 135 for charter or Part 121 for scheduled airlines, though certain subparts provide a bridge for large aircraft under Fractional ownership programs operating under Management Specifications. The regulation interfaces with other critical parts, such as Part 61 for pilot certification and Part 43 for maintenance standards, to create a cohesive regulatory system.

Operating Rules and Limitations

This section details the fundamental rules for safe flight, covering requirements from preflight action and aircraft familiarization to specific in-flight procedures. It prescribes minimum safe altitudes, VFR weather minimums for different classes of airspace, and IFR flight plan requirements for operations in Class A airspace or under instrument meteorological conditions. Critical limitations include restrictions on careless or reckless operation, the prohibition of dropping objects, and specific rules for operating near other aircraft, such as right-of-way rules and formation flight authorizations. Additional subparts govern operations at high-traffic airports like John F. Kennedy International Airport under special traffic management rules and establish fuel requirements for IFR flights and VFR flights to ensure safe arrival at the intended destination.

Pilot and Crewmember Requirements

While Part 61 establishes certification standards, this section defines the operational requirements for pilots and other flight crewmembers. It mandates that the pilot-in-command is directly responsible for, and the final authority as to, the operation of the aircraft. Requirements include holding an appropriate and current pilot certificate, such as a private pilot certificate or airline transport pilot certificate, and a valid medical certificate from the FAA Aeromedical Division. For flights under IFR or in Class B airspace, the pilot must possess an instrument rating. The rules also specify crew complement, requiring a second-in-command for aircraft type-certificated for more than one pilot, and establish duty period and rest requirements for certain corporate flight departments to combat fatigue.

Aircraft Airworthiness and Maintenance

These rules ensure aircraft are in a condition for safe operation, tying into the maintenance regulations of Part 43. The owner or operator is responsible for maintaining the aircraft in an airworthy condition, including compliance with all applicable Airworthiness Directives (ADs) issued by the FAA. Required inspections include the annual inspection performed by a certified Airframe and Powerplant (A&P) mechanic with an Inspection Authorization (IA) and the 100-hour inspection for aircraft used for hire. Prior to flight, the pilot is required to review the aircraft maintenance records and ensure all inoperative instruments and equipment are properly documented and deferred in accordance with the Minimum Equipment List (MEL) or the rules for specific VFR flight.

Special Flight Operations

This segment addresses operations that require specific rules beyond general flight, providing waivers or outlining procedures for unique activities. It covers the requirements for obtaining a Letter of Authorization (LOA) or waiver for operations such as aerobatic flight over congested areas, antique aircraft exhibition, or experimental aircraft flight testing. Other specialized operations governed here include air racing and air show performances, agricultural aircraft operations, and the specific, highly restrictive rules for operating a Restricted category aircraft. The regulation also establishes protocols for operations in designated special use airspace like Military Operations Areas (MOAs) or over sensitive national security sites.